Railcar bolster casting method

ABSTRACT

A coring arrangement for casting a railcar bolster, including left and right half center cores having faces defining internal surfaces of each of the bolster top, bottom, and opposing side walls from the bolster central transverse plane to a point between the left and right friction shoe pocket inner and outer walls. The coring arrangement also includes left and right top half end cores having faces defining an internal surface of the bolster top wall, and of each opposing side wall from a point between the left and right friction shoe pocket inner and outer walls to the ends of the bolster. Left and right bottom half end cores have faces defining an internal surface of the bolster bottom wall, and of each opposing side wall from a point between the left and right friction shoe pocket inner and outer walls to the ends of the bolster.

BACKGROUND OF THE INVENTION

[0001] Railcar bolsters are steel castings. Bolsters, like many other steel castings, are cast in a mold. Typically, the mold has a top or cope section and a bottom or drag section. The cope and drag sections of the mold are each contained in a flask. A pattern is placed over one end of each flask and sand is rammed over the pattern, thereby compacting the sand around the pattern. Sand is rammed into the flask until the flask is filled with sand. The pattern is then removed leaving an impression of the casting's external surfaces in the compacted cope and drag section mold sand.

[0002] Bolsters also typically have hollow sections. The hollow sections are created by cores placed in the drag mold. Cores are supported in the mold on each other, using core prints, or with chaplets. Chaplets can cause stress risers in the casting and are expensive. Supporting cores on other cores reduces dimensional control. Core prints are the preferred way to support and locate cores in the mold. Cores define the internal surfaces of the bolster walls in the hollow sections. Cores may occasionally form the outer surface of the casting. This occurs where a ledge or other overhang appears on the casting. Without a core to form the external surface of the casting, the pattern could not be removed from the mold.

[0003] Cores are made from sand and often within a core blowing machine. The sand contains a binding agent to maintain the core's integrity while handling the core during the casting process. Typical binders include phenolic resin, polyurethane, and sodium silicate. A popular core sand binder is Ashland Inc.'s Isocure® binder, which is preferably used with the present invention.

[0004] Cores are made in core boxes. The core box includes a drag section and a cope section. To make a core with a core blower, the core box cope and drag sections are fastened together, and the core box placed on the core blower. Tooling is required to fit the particular core box to the core blower. Different tooling is generally necessary to fit each different core box to the core blower. The requirement for and manufacture of such tooling is well known in the art.

[0005] The core blower produces cores by blowing sand into the core box. The core blower typically uses sand containing binders such as Isocure® that cure the core in the core box. The core blower injects curing gas into the core box to cure the core. Isocure® uses an amine gas to catalyze the curing process. The cope and drag sections of the core box are separated leaving the core.

[0006] To cast the bolster, the mold's cope section is placed on top of the drag section forming a cavity in the mold. Molten metal is poured into the mold cavity to produce the bolster walls. After the molten metal is poured into the mold, the steel increases in density due to shrinkage as it solidifies. In steel casting, metal reservoirs called risers are used to account for the steel density change as it cools. After the casting has solidified, the risers are removed.

[0007] Steel casting solidification defects adversely affect casting performance. To avoid solidification related defects, the casting walls near the risers should be the last portions to solidify for the riser to feed the casting with liquid metal during solidification. It is, therefore, desirable for the casting wall thickness to be designed to facilitate directional solidification. Directional solidification dictates that portions of the casting furthest from the riser solidify first, solidification proceeding directionally toward the riser, with portions of the casting closest to the riser solidifying last.

[0008] Directional solidification can be controlled by the casting wall thickness. Solidification time is proportional to wall thickness. The thicker the casting wall, the longer the solidification time. To facilitate directional solidification, the casting wall thickness near the riser should be greater or equal to the casting wall thickness in casting portions furthest from the riser.

[0009] Pattern, core, and core print design affect casting wall thickness. Pattern and corebox geometries require taper angles so the pattern can be removed from the sand or for the core to be removed from the corebox. These taper angles are called draft. The patterns, cores, and core prints must be designed so that directional solidification requirements for casting wall thickness are not violated by draft. However, optimal pattern, core, or corebox design may violate directional solidification.

SUMMARY OF THE INVENTION

[0010] In one embodiment, the present invention provides a coring arrangement for casting a railcar bolster. The coring arrangement is located in a mold. The bolster has hollow sections and a left end and right end. The bolster also has a top wall, a bottom wall, and a pair of opposing side walls connecting the top wall and bottom wall. The bolster further includes a central transverse plane, a pair of left friction shoe pockets, and a pair of right friction shoe pockets. The pair of left friction shoe pockets and pair of right friction shoe pockets each have inner and outer walls. The coring arrangement includes a left half center core having faces defining an internal surface of each of the bolster top wall, bottom wall, and opposing side walls from the bolster central transverse plane to a point between the pair of left friction shoe pocket inner and outer walls. It also includes a right half center core having faces defining an internal surface of each of the bolster top wall, bottom wall, and opposing side walls from the bolster central transverse plane to a point between the pair of right friction shoe pocket inner and outer walls. The coring arrangement also includes a left top half end core having faces defining an internal surface of the bolster top wall, and an internal surface of each opposing side wall from a point between the left friction shoe pocket inner and outer walls to the left end of the bolster. A left bottom half end core has faces defining an internal surface of the bolster bottom wall, and an internal surface of each opposing side wall from a point between the left friction shoe pocket inner and outer walls to the left end of the bolster. The coring arrangement also includes a right top half end core having faces defining an internal surface of the bolster top wall, and an internal surface of each opposing side wall from a point between the right friction shoe pocket inner and outer walls to the right end of the bolster. A right bottom end core has faces defining an internal surface of the bolster bottom wall, and an internal surface of each opposing side wall from a point between the right friction shoe pocket inner and outer walls to the right end of the bolster.

[0011] In another embodiment, the present invention provides a railcar bolster having a left end and a right end, a top wall, a bottom wall, a pair of opposing side walls connecting the top wall and bottom wall. The bolster also has a central transverse plane, a pair of left friction shoe pockets, and a pair of right friction shoe pockets. The pair of left friction shoe pockets and pair of right friction shoe pockets each have inner walls and outer walls. The bolster bottom wall has at least four bottom wall openings, two bottom wall openings on either side of the bolster central transverse plane and central longitudinal plane. Each bottom wall opening accommodates a bottom wall opening core print extending through the opening. The bolster also includes a pair of left top end openings in the bolster top wall between the bolster left end and the inner walls of the pair of left friction shoe pockets, and a pair of right top end openings in the bolster top wall between the bolster right end and the inner walls of the pair of right friction shoe pockets. Each top end opening accommodates a top end opening core print extending therethrough. The bolster further has a pair of left bottom end openings in the bolster bottom wall between the outer walls of the pair of left friction shoe pockets and the bolster central transverse plane, and a pair of right bottom end openings in the bolster bottom wall between the outer walls of the pair of right friction shoe pockets and the bolster central transverse plane. Each bottom end opening accommodates a bottom end opening core print extending therethrough.

[0012] In a further embodiment, the present invention provides a method of casting a railcar bolster. The method includes the steps of inserting cores into a mold to define internal surfaces of the bolster. The cores are made in coreboxes. The cores include a left half center core, a right half center core, a left top half end core, a right top half end core, a left bottom half end core, a right bottom half end core, a left friction wedge core, and a right friction wedge core. The left half center core and right half center core are identical. The left top half end core and right top half end core are identical. The left bottom half end core and right bottom half end core are identical, and the left friction wedge core and right friction wedge core are identical. In the method, all of the cores are made in two coreboxes.

[0013] The present invention provides a casting method and coring arrangement that facilitates directional solidification while minimizing core and corebox production and maintenance costs. The present invention also provides core location and support that avoids chaplets and cores located by other cores. Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the figures.

BRIEF DESCRIPTION OF THE FIGURES

[0014]FIG. 1 is a plan view of a railcar sideframe.

[0015]FIG. 2 is a perspective plan view of a railcar bolster made in accord with an embodiment of the present invention.

[0016]FIG. 3 is a bottom perspective view of a railcar bolster made in accord with an embodiment of the present invention.

[0017]FIG. 4 is an enlarged bottom perspective view of an end of a railcar bolster made in accord with an embodiment of the present invention.

[0018]FIG. 5 is an enlarged top perspective view of an end of a railcar bolster made in accord with an embodiment of the present invention.

[0019]FIG. 6 is an enlarged perspective plan view of a central portion of a railcar bolster made in accord with an embodiment of the present invention.

[0020]FIG. 7 is a perspective view of an internal portion of a railcar bolster made in accord with an embodiment of the present invention.

[0021]FIG. 8 is a perspective plan view of a coring arrangement in accord with an embodiment of the present invention.

[0022]FIG. 9 is a plan perspective view of a half center core in accord with an embodiment of the present invention.

[0023]FIG. 10 is an additional plan perspective view of a half center core in accord with an embodiment of the present invention.

[0024]FIG. 11 is bottom perspective view of a half center core in accord with an embodiment of the present invention.

[0025]FIG. 12 is a schematic drawing illustrating core support in accord with an embodiment of the present invention.

[0026]FIG. 13 is a schematic drawing illustrating prior art core support.

[0027]FIG. 14 is a top perspective view of a top half end core in accord with an embodiment of the present invention.

[0028]FIG. 15 is a bottom perspective view of a top half end core in accord with an embodiment of the present invention.

[0029]FIG. 16 is a top perspective view of a bottom half end core in accord with an embodiment of the present invention.

[0030]FIG. 17 is a bottom perspective view of a bottom half end core in accord with an embodiment of the present invention.

[0031]FIG. 18 is a side view of a top half end core, bottom half end core, and half center core in accord with an embodiment of the present invention.

[0032]FIG. 19 is a perspective view of a friction wedge core in accord with an embodiment of the present invention.

[0033]FIG. 20 is a perspective view of a half center core and friction wedge core in accord with an embodiment of the present invention.

[0034]FIG. 21 is a perspective view of a friction pocket core in accord with an embodiment of the present invention.

[0035]FIG. 22 illustrates a corebox used in accord with an embodiment of the present invention.

[0036]FIG. 23 illustrates a corebox used in accord with an embodiment of the present invention.

[0037]FIG. 24 is a schematic drawing illustrating directional solidification.

[0038]FIG. 25 is a schematic drawing illustrating lack of directional solidification.

[0039]FIG. 26 is a schematic drawing illustrating prior art coring for a railcar bolster.

[0040]FIG. 27 is a schematic drawing illustrating prior art coring for a railcar bolster.

[0041]FIG. 28 is a schematic drawing illustrating coring for a railcar bolster in accord with an embodiment of the present invention.

[0042]FIG. 29 is a schematic drawing illustrating prior art coring for a railcar bolster.

[0043]FIG. 30 is a schematic drawing illustrating prior art coring for a railcar bolster.

[0044]FIG. 31 is a schematic drawing illustrating coring for a railcar bolster in accord with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0045]FIG. 1 shows a typical railcar truck 10. There are two trucks 10 per railcar. The railcar truck 10 includes two wheelsets 12, a pair of sideframes 14, and a bolster 16. Each sideframe 14 accommodates the bearings 17 of the wheelsets 12. The sideframes 14 rest on the wheelsets 12. The bolster 16 extends between the sideframes 14. The bolster 16 is supported by the sideframes 14 on springs 18. The springs 18 may be supported directly on the sideframe 14, or on an intermediate assembly (not shown).

[0046]FIG. 2 shows a bolster 16 made in accord with an embodiment of the present invention. The bolster 16 has a top wall 20, a bottom wall 22, and a pair of opposing side walls 24. The bolster 16 also has a central transverse plane 26 having the bolster defining a left end 28 and a right end 30. The bolster 16 has a center bowl 32. The center bowl 26 has a ledge 34. An opening 36 in the center bowl 32 accepts a king pin (not shown). The bolster 16 also has a left brake beam opening 38 and right brake beam opening 40 in each opposing side wall 24. The bolster 16 also has a left side window 42 and right side window 44 in each opposing side wall 24.

[0047] At the left end 28 of the bolster 16 is a pair of left friction shoe pockets 46. The pair of left friction shoe pockets 46 each have inner walls 48 and outer walls 50. At the right end 30 of the bolster 16 is a pair of right friction shoe pockets 52 (FIG. 4). The pair of right friction shoe pockets 52 also has inner walls 54 and outer walls 56.

[0048]FIG. 3 is a bottom perspective view of the bolster of FIG. 2. In the bottom wall 22 of the bolster 16 are bottom wall openings 62. Two bottom wall openings 62 are on either side of the central transverse plane 26 and a central longitudinal plane 64 of the bolster 16.

[0049]FIG. 4 is a bottom view of the right end 30 of the bolster 16. FIG. 4 shows a pair of right bottom end openings 66 in the bottom wall 22 of the bolster 16. The pair of right bottom end openings 66 are located toward the central transverse plane 26 from the pair of right friction shoe pockets 52. The left end 28 and right end 30 are symmetrical. An identical pair of left bottom end openings 67 are present in the left end 28 of the bolster 16.

[0050]FIG. 4 shows the inner walls 54 and outer walls 56 of the pair of right friction shoe pockets 52. The pair of right friction shoe pockets 52 also includes a pair of right friction shoe wedges 68. An identical pair of left friction shoe wedges 69 is present at the pair of left friction shoe pockets 46 at the left end 28 of the bolster 16 (FIG. 3). A right spring set surface 70 is located at the right end 30 of the bolster 16. The right spring set surface 70 rests on the springs 18. The right spring set surface 70 also contains lugs 72 to locate the springs 18. An identical left spring set surface 71 is located at the left end 28 of the bolster 16 (FIG. 3).

[0051]FIG. 5 is a top view of the right end 30 of the bolster 16. The top wall 20 of the bolster includes a pair of right top end openings 74. The pair of right top end openings 74 is located toward the right end 30 of the bolster 16 from the pair of right friction shoe pockets 52. An identical pair of left top end openings 75 is located at the left end 28 of the bolster 16 (FIG. 2).

[0052]FIG. 6 shows the center bowl 26 and a ledge 34 overhanging one of the opposing side walls 24. Ledges 34 overhang each of the opposing side walls 24. FIG. 6 also shows internal ribs 76 in the interior of the bolster 16. The left and right brake beam openings 38 and 40 extend through the internal ribs 76. FIG. 6 also shows the left and right side windows 42 and 44.

[0053]FIG. 7 is a perspective view with a portion of the bolster 16 cut away. FIG. 7 shows an internal surface 78 of one opposing side wall 24. It also shows an internal surface 80 of the bottom wall 22 and the pair of left friction shoe pockets 46. It further shows a partial bottom wall opening 62, left brake beam opening 38, and left side window 42.

[0054]FIG. 8 shows a coring arrangement 82 in accord with an embodiment of the present invention. The coring arrangement 82 includes a left half center core 84, a right half center core 86, a left top half end core 88, a right top half end core 90, a left bottom half end core 92, and a right bottom half end core 94. The coring arrangement 82 also includes a left friction wedge core 96 and a right friction wedge core 98. The coring arrangement 82 is placed a mold (not shown) to define internal surfaces and some external surfaces of the bolster 16. The mold has a cope section and a drag section as is well known in the art.

[0055]FIG. 9 shows a perspective view of the left half center core 84. The left half center core 84 has a mating surface 100 that meets with the right half center core 86 at the central transverse plane 26 of the bolster 16. The left half center core 84 has a top wall defining face 102 that defines internal surfaces of the bolster top wall 20, a bottom wall defining face 104 that defines internal surfaces of the bolster bottom wall 22 (FIG. 11), and a pair of side wall defining faces 106 that define internal surfaces of the pair of opposing bolster side walls 24 to the left of the central transverse plane 26 of the bolster 16. The left half center core 84 preferably defines internal surfaces of the top wall 20, bottom wall 22, and opposing side walls 24 from the central transverse plane 26 to a point between the inner walls 48 and outer walls 50 of the pair of left friction shoe pockets 46.

[0056] It should be kept in mind that the right half center core 86 is the mirror image of the left half center core 84. The right half center core 86 has top wall defining face 108 that defines internal surfaces of the bolster top wall 20, a bottom wall defining face 110 that defines internal surfaces of the bolster bottom wall 22, and a pair of side wall defining faces 112 that define internal surfaces of the pair of opposing bolster side walls 24 to the right of the central transverse plane 26 of the bolster 16 (FIG. 8). The right half center core 86 preferably defines internal surfaces of the top wall 20, bottom wall 22, and opposing side walls 24 from the central transverse plane 26 to a point between the inner walls 54 and outer walls 56 of the pair of right friction shoe pockets 52. The left and right half center cores 84 and 86 also have surfaces 114 and 116 that define the internal ribs 76 of the bolster 16.

[0057] A left brake beam opening core print 118 extending from each opposing side wall defining face 106 defines the left brake beam openings 38 of the bolster 16. Left side window core prints 120 define the left side windows 42 of the bolster 16. A right brake beam opening core print 122 extending from each opposing side wall defining face 112 defines the right brake beam openings 40 of the bolster 16 (FIG. 8). Right side window core prints 124 define the right side windows 44 of the bolster 16.

[0058]FIG. 10 shows a left perspective view of the left half center core 84. At a left end 126 of the left half center core 84 is a weight bearing surface 128. Faces 130 define the interior surfaces of the inner walls 48 of the pair of left friction shoe pockets 46. The right half center core 86 has a similar weight bearing surface and faces.

[0059]FIG. 11 is a bottom perspective view of the left half center core 84. Bottom wall opening core prints 132 extending from the bottom wall defining face 104 of the left half center core 84. The bottom wall opening core prints 132 preferably extend into the mold. Similarly, the right half center core 86 has a pair of bottom wall opening core prints extending from its bottom wall into the mold. The bottom wall core prints of both the left and right half center cores 84 and 86 extend through and create the bottom wall openings 62 in the bolster 16.

[0060]FIG. 12 shows how the left and right half center cores 84 and 86 are supported using the bottom wall opening core prints 132 in accord with an embodiment of the present invention. The bottom wall opening core prints 132 support and stabilize the left and right half center cores 84 and 86 in the mold without the use of chaplets. FIG. 13 shows how the left and right half center cores 84 and 86 would have to be supported if only one core print 131 were used. Chaplets 133 have to support and stabilize the core.

[0061]FIG. 14 is a top view of the left top half end core 88. The left top half end core 88 preferably has a top wall defining face 134 that defines an internal surface of the bolster top wall 20 from a point between the inner walls 48 and outer walls 50 of the left pair of friction shoe pockets 46 to the left end 28 of the bolster 16. The left top half end core 88 also has a pair of opposing side wall defining faces 136 that define an internal surface of each of the opposing side walls 24 from a point between the inner walls 48 and outer walls 50 of the pair of left friction shoe pockets 46 to the left end 28 of the bolster 16.

[0062] The left top half end core 88 also has a pair of left top end opening core prints 138 extending from the top wall defining face 134. The pair of left top end opening core prints 138 preferably extend into the mold and prevent the left top half end core 88 and bottom half end core 92 from floating in the mold, and define the pair of left top end openings 75 in the bolster 16.

[0063] Similarly, the right top half end core 90 has a top wall defining face 140 that defines an internal surface of the bolster top wall 20 from a point between the inner walls 54 and outer walls 56 of the pair of right friction shoe pockets 52 to the right end 30 of the bolster 16 (FIG. 8). The right top half end core 90 also has a pair of opposing side wall defining faces 142 that define an internal surface of each of the opposing side walls 24 from a point between the inner walls 54 and outer walls 56 of the pair of right friction shoe pockets 52 to the left end 30 of the bolster 16.

[0064] The right top half end core 90 also has a pair of right top end opening core prints 144 extending from the top wall defining face 140. The pair of right top end opening core prints 144 preferably extend into the mold, and define the pair of right top end openings 74 in the bolster 16.

[0065]FIG. 15 is a bottom view of the left top half end core 88. The left top half end core 88 includes a bottom surface 146. The bottom surface 146 has a plurality of openings 148. Each of the openings 148 has an upper face 150. The purpose of the openings 148 is discussed below.

[0066] Like the left top half end core 88, the right top half end core 90 includes a bottom surface. The bottom surface of the right top half end core 90 also has a plurality of openings. Each of the openings has an upper face.

[0067]FIGS. 16 and 17 are top and bottom views, respectively, of the left bottom half end core 92. The left bottom half end core 92 has a bottom wall defining face 152 that defines an internal surface of the bottom wall 22 of the bolster 16, and a pair of side wall defining faces 154 that define an internal surface of each of the opposing side walls 24 of the bolster 16 left of the central transverse plane 26. The left bottom half end core 92 preferably defines an internal surface of the bottom wall 22, and each of the opposing side walls 24 from a point between the inner walls 48 and outer walls 50 of the pair of left friction shoe pockets 46 to the left end 28 of the bolster 16.

[0068] Similarly, right bottom half end core 94 has a bottom wall defining face that defines an internal surface of the bottom wall 22 of the bolster 16, and a pair of side wall defining faces that define an internal surface of each of the opposing side walls 24 of the bolster 16 right of the central transverse plane 26. The right bottom half end core 94 preferably defines an internal surface of the bottom wall 22, and each of the opposing side walls 24 from a point between the inner walls 54 and outer walls 56 of the pair of right friction shoe pockets 52 to the right end 30 of the bolster 16.

[0069] The left bottom half end core 92 has an upper surface 156. Extending from the upper surface 156 is a plurality of lugs 158. Each of the lugs 158 extends into a corresponding opening 148 in the left top half end core 88. The lugs 158 and openings 148 stabilize and locate the left top half end core 88 with respect to the left bottom half end core 92. Each of the lugs 158 also has a top face 160. When the lugs 158 extend into the openings 148, the upper faces 150 of the openings 148 are spaced from the top faces 160 of the lugs 158. The weight of the left top half end core 88 is supported on the upper surface 156 of the left bottom half end core 92.

[0070] Similarly, the right bottom half end core 94 has an upper surface. Extending from the upper surface is a plurality of lugs. Each of the lugs extends into a corresponding opening in the right top half end core 90. The lugs and openings stabilize and locate the right top half end core 90 with respect to the right bottom half end core 94. Each of the lugs also has a top face. When the lugs extend into the openings, the upper faces of the openings are spaced from the top faces of the lugs. The weight of the right top half end core 90 is supported on the upper surface of the right bottom half end core 94.

[0071] As shown in FIG. 17, the left bottom half end core 92 has a shelf 162. The shelf 162 rests on the weight bearing surface 128 of the left half center core 84 to support the left bottom half end core 92 in the mold. The right bottom half end core 94 has a similar shelf. The right bottom half end core 94 shelf rests on a weight bearing surface of the right half center core 86.

[0072]FIG. 18 shows the left half center core 84, left top half end core 88, and left bottom half end core 92 as they sit in the mold. The shelf 162 of the left bottom half end core 92 rests on the weight bearing surface 128 of the left half center core 84. The bottom surface 146 of the left top half end core 88 rests on the top surface of the left bottom half end core 92. The lugs 158 on the upper surface 156 of the left bottom half end core 92 extend into the openings 148 in the bottom surface 146 of the left top half end core 88.

[0073] Similarly, the shelf of the right bottom half end core 94 rests on the weight bearing surface of the right half center core 86. The bottom surface of the right top half end core 90 rests on the top surface of the right bottom half end core 94. Lugs on the top surface of the right bottom half end core 94 extend into the openings in the bottom surface of the right top half end core 90.

[0074]FIG. 19 is a perspective view of the left friction wedge core 96. The left friction wedge core 96 includes left friction shoe pocket inner wall defining faces 164 that define the external surfaces of the inner walls 48 of the pair of left friction shoe pockets 46. The left friction wedge core 96 also has left friction shoe pocket outer wall defining faces 166 that define the external surfaces of the outer walls 50 of the pair of left friction shoe pockets 46. The left friction wedge core 96 further includes left friction shoe wedge defining faces 168 that define the external surfaces of the left friction shoe wedges.

[0075] The left friction wedge core 96 also has a left spring surface set defining face 170 that defines the external surface of the left spring set surface of the bolster 16. Extending from the left spring set surface defining face 170 is a pair of lugs 172. As shown in FIG. 20, the left half center core 84 rests upon the lugs 172 to support the weight of the left half center core 84 in the mold. The lugs define the left and right bottom end openings 66 and 67 in the bolster 16.

[0076] The right friction wedge core 98 includes has right friction shoe pocket inner wall defining faces that define the external surfaces of the inner walls 54 of the pair of right friction shoe pockets 52. The right friction wedge core 98 also has right friction shoe pocket outer wall defining faces that define the external surfaces of the outer walls 56 of the pair of right friction shoe pockets 52. The right friction wedge core 98 further includes right friction shoe wedge defining faces that define the external surfaces of the right friction shoe wedges 68.

[0077] The right friction wedge core 98 also has a right spring set surface defining face that defines the external surface of the right spring set of the bolster 16. Extending from the right spring set surface defining face is a pair of lugs. Similar to FIG. 20, the right half center core 86 rests upon the lugs to support the weight of the right half center core 86 in the mold.

[0078] In an alternative embodiment, a friction pocket core 174 may be used in place of the friction wedge cores 96 and 98 (FIG. 21). For one bolster 16, a total of four friction pocket cores 174 are required, two for each of the pair of left and right friction shoe pockets 46 and 52. If friction pocket cores 174 are used, the bolster spring set external surfaces are mostly defined by the mold sand.

[0079] The friction pocket core 174 has a friction shoe wedge defining face 176. The friction shoe wedge defining face 176 defines the external surface of one friction shoe wedge of the bolster 16. The friction pocket core 174 also has a friction pocket inner wall defining face 178 and a friction pocket outer wall defining face 180 for defining the external surfaces of one of the friction pocket inner and outer walls 48, 50, 54, or 56 of the bolster 16.

[0080] The cores of coring arrangement 82 of the present invention are preferably made from sand using a core blowing machine. The use of core blowers to make cores is well known in the art. Core blowing machines such as those manufacture by Equipment Merchants International, Inc. or Laempe can be used with the present invention.

[0081] Corebox tooling costs and core production cycle time constitute a significant portion of the total cost of producing bolster castings. To minimize production costs, bolster castings must be produced such that core production machines and coreboxes are used to their full potential. The number of coreboxes required to produce the cores should be minimized so that core machine downtime is also minimized when coreboxes are changed on the core machines. Fewer coreboxes also lowers corebox maintenance costs. Core geometry affects the number of coreboxes and core production cycles required to produce a bolster casting. Core geometry must be optimized to reduce costs.

[0082] The present invention contemplates use of two core blowing machines used to produce the bolster using the above-recited cores, a large core blowing machine and a small core machine. FIG. 22 shows an embodiment of the present invention where one large corebox 182 is used on one core blowing machine to make the left or right half center cores 84 and 86 and the left or right friction wedge cores 96 and 98. The left and right half center cores 84 and 86, left and right top half end cores 88 and 90, and left and right bottom half end cores 92 and 94, being smaller cores, are all preferably made on a separate core machine or core blower in a single small corebox.

[0083] The left and right half center cores 84 and 86 are identical mirror images of each other. The same is true of the left and right friction wedge cores 96 and 98. Thus, without changing the large corebox, with two production cycles make both left and right half center cores 84 and 86 and the left and right friction wedge cores 96 and 98. Similarly, the left and right top half end cores 88 and 90 are identical mirror images if each other as are the left and right bottom end cores 92 and 94. Without changing the small corebox, two production cycles can make all of the remaining cores for the bolster. The small corebox makes one top half and one bottom half end core. Using the method of the present invention, a total of only four core production cycles are required to make a bolster, two with the large corebox and two with the small corebox. FIG. 23 shows a large corebox 184 that instead of containing one friction wedge core 96 or 98, holds two friction pocket cores 174.

[0084]FIG. 24 illustrates a casting design that facilitates directional solidification in a casting wall section 186. Directional solidification is a term used in the foundry art to express the desired order in which casting wall sections solidify. A riser 188 acts as a reservoir to store molten metal to make up for casting metal shrinkage as it cools. The proper order for solidification is for casting wall sections farthest from the riser to solidify first with solidification time increasing the closer casting wall sections are to the riser. Casting wall sections closest to the riser are to solidify last. Directional solidification occurs when this solidification order is achieved. Holding other factors constant, the thicker the casting wall section, the longer the solidification time. Near the riser 188, the casting wall section 186 has a thickness 190. At a point furthest from the riser 188, the casting wall section 186 has a thickness 192. Intermediate between the riser 188 and thickness 192, the casting wall has a thickness 194. To maintain directional solidification, the casting wall thickness 192 must be less than casting wall thickness 194, which must be less than thickness 190. Because the casting wall thickness 192 is less than casting wall thicknesses 194 or 190, metal at thickness 192 will solidify there before it solidifies at the riser 188.

[0085]FIG. 25 illustrates a casting design that does not facilitate directional solidification in a casting wall section 196. In FIG. 25, a casting wall thickness 198 farthest from the riser 200 is greater than the casting wall thickness 202 closest to the riser 200. In this design, metal will solidify near the riser 200 first. Thus, molten metal will not be able to flow from the riser 188 to the casting wall at 198, and metal shrinkage problems will occur.

[0086]FIG. 26 shows a prior art coring method for forming the left and right brake beam openings in a bolster. FIG. 26 is a schematic cross-sectional view of a brake beam opening 204. The bolster top wall is depicted at 206, the side wall at 207, and the bottom wall at 208. A top portion 210 of the bolster side wall 207 is above the brake beam opening 204, and a bottom portion 212 of the bolster side wall 207 is below the brake beam opening 204. An internal core 214 forms the brake beam opening 204, does not protrude into the sand, but stops at the outside edge 216 of the casting profile. A separate bowl core 215 forms bottom surfaces 217 of the bolster center bowl ledge 219.

[0087]FIG. 27 is a schematic cross-section view illustrating another prior art coring method for forming a bolster brake beam opening 218. The bolster top wall 220, bottom wall 222, and side wall 224 are shown. A single core 226 extends through the brake beam opening 218 into the mold and forms the bottom surface 227 of the center bowl ledge 228 and an external surface 229 of the side wall 224. However, in this prior art design, the bottom portion 230 of the side wall 224 does not facilitate directional solidification because the side wall thickness 232 is less than the side wall thickness 234.

[0088]FIG. 28 shows a left or right brake beam opening 38 or 40 made in accord with an embodiment of the present invention. The left and right half center cores 84 and 86 have left and right brake beam opening core prints 118 and 122 extending from each side wall defining face 106 and 112. The left and right brake beam opening core prints 118 and 122 extend through the brake beam openings 38 and 40 into the mold. The left and right brake beam opening core prints 118 and 122 also define half of the center bowl ledges 34 in a manner to facilitate directional solidification each opposing side wall 24. The thickness at the top 236 of each side wall 24 is greater than that at the bottom 238 of the side wall 24. The thickness 240 is intermediate the thickness at top 236 and bottom 238. The left and right brake beam opening core print 118 and 122 also preferably each define an external surface 242 of the side walls 24.

[0089]FIG. 29 is a cross-sectional view of prior art coring for the side windows 42 and 44 of the bolster 16. A main pattern parting line 244 is the line where the cope mold and drag mold (not shown) separate. The side windows 42 and 44 are below the main pattern parting line 244. In the prior art, an internal core 246 formed the inner surfaces 248 of the bolster 16. A separate core 250 formed the side windows 42 and 44 and the portion 251 between the top 252 of the side windows 42 and 44 and the main pattern parting line 244.

[0090]FIG. 30 is a cross-section view of another prior art coring for the side windows 42 and 44 of the bolster 16. One core 254 forms the internal surfaces 256 of the bolster 16 and the side windows 42 and 44. The core 254 extends into the mold and defines the portion between the top of the side windows 42 and 44 and the main pattern parting line 257. The bottom 258 of the bolster side wall 260 has a thickness that does not facilitate directional solidification because the bottom 258 is thicker at 262 than at 264.

[0091]FIG. 31 shows an embodiment of the present invention. The left half center core 84 has a left side window core print 120 defining the left side window 42. The left side window core print 120 extends into the mold and defines a portion of the external surface 266 of the bolster 16 from the left side window 42 to the main pattern parting line 267. Moreover, the thickness 268 of the bolster side wall 24 above the left side window 42 is greater than the thickness 270 of the side wall 24 below the left side window 42, which in turn in greater than the thickness 272 of the side wall 24 near the bottom wall 22. Thus, this design maintains directional solidification.

[0092] Similarly, the right half center core 86 has a right side window core print 124 defining the right side window 44. The right side window core print 124 extends into the mold and defines a portion of the external surface of the bolster 16 from the right side window 44 to the main pattern parting line 267. Moreover, the thickness of the bolster side wall 24 above the right side window 44 is greater than the thickness of the side wall 24 below the right side window 44, which in turn in greater than the thickness of the side wall 24 near the bottom wall 22.

[0093] It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims. 

The invention is claimed as follows:
 1. A coring arrangement for casting a railcar bolster, the coring arrangement located in a mold, the bolster having hollow sections, the bolster also having a top wall, a bottom wall, and a pair of opposing side walls connecting the top wall and bottom wall, the bolster further having a central transverse plane, the coring arrangement comprising: a left half center core having faces defining an internal surface of each of the bolster top wall, bottom wall, and opposing side walls left of the central transverse plane; a right half center core having faces defining an internal surface of each of the bolster top wall, bottom wall, and opposing side walls right of the central transverse plane; a left top half end core having faces defining an internal surface of the bolster top wall, and an internal surface of each opposing side wall left of the central transverse plane; a left bottom half end core having faces defining an internal surface of the bolster bottom wall, and an internal surface of each opposing side wall left of the central transverse plane; a right top half end core having faces defining an internal surface of the bolster top wall, and an internal surface of each opposing side wall right of the central transverse plane; and a right bottom end core having faces defining an internal surface of the bolster bottom wall, and an internal surface of each opposing side wall right of the central transverse plane.
 2. The coring arrangement of claim 1 wherein the bolster includes a pair of left friction shoe pockets and a pair of right friction shoe pockets, the pair of left friction shoe pockets and pair of right friction shoe pockets each having inner and outer walls, and wherein the left half center core defines an internal surface of each of the bolster top wall, bottom wall, and opposing side walls from the bolster central transverse plane to a point between the pair of left friction shoe pocket inner and outer walls.
 3. The coring arrangement of claim 1 wherein the bolster includes a pair of left friction shoe pockets and a pair of right friction shoe pockets, the pair of left friction shoe pockets and pair of right friction shoe pockets each having inner and outer walls, and wherein the right half center core defines an internal surface of each of the bolster top wall, bottom wall, and opposing side walls from the bolster central transverse plane to a point between the pair of right friction shoe pocket inner and outer walls.
 4. The coring arrangement of claim 1 wherein the bolster has a left end and a right end, a pair of left friction shoe pockets and a pair of right friction shoe pockets, the pair of left friction shoe pockets and pair of right friction shoe pockets each having inner and outer walls, the left top half end core defining an internal surface of the bolster top wall and an internal surface of each of the opposing side walls from a point between the pair of left friction shoe pocket inner and outer walls to the left end of the bolster.
 5. The coring arrangement of claim 1 wherein the bolster has a left end and a right end, a pair of left friction shoe pockets and a pair of right friction shoe pockets, the pair of left friction shoe pockets and pair of right friction shoe pockets each having inner and outer walls, the right top half end core defining an internal surface of the bolster top wall and an internal surface of each of the opposing side walls from a point between the pair of right friction shoe pocket inner and outer walls to the right end of the bolster.
 6. The coring arrangement of claim 1 wherein the bolster has a left end and a right end, a pair of left friction shoe pockets and a pair of right friction shoe pockets, the pair of left friction shoe pockets and pair of right friction shoe pockets each having inner and outer walls, the left bottom half end core defining an internal surface of the bolster bottom wall and an internal surface of each of the opposing side walls from a point between the pair of left friction shoe pocket inner and outer walls to the left end of the bolster.
 7. The coring arrangement of claim 1 wherein the bolster has a left end and a right end, a pair of left friction shoe pockets and a pair of right friction shoe pockets, the pair of left friction shoe pockets and pair of right friction shoe pockets each having inner and outer walls, the right bottom half end core defining an internal surface the bolster bottom wall and an internal surface of each of the opposing side walls from a point between the pair of right friction shoe pocket inner and outer walls to the right end of the bolster.
 8. The coring arrangement of claim 1 wherein the bolster includes a left spring set surface, a right spring set surface, a pair of left friction shoe pockets, and a pair of right friction shoe pockets, the pair of left friction shoe pockets and pair of right friction shoe pockets each having inner walls, outer walls, and a pair of friction wedges, the coring arrangement further comprising a left friction wedge core having faces defining external surfaces of the inner walls, outer walls, and a pair of friction wedges of the pair of left friction shoe pockets and the left spring set surface, and a right friction wedge core having faces defining external surfaces of the inner walls, outer walls, and pair of friction wedges of the pair of right friction shoe pockets and the right spring set surface.
 9. The coring arrangement of claim 8 wherein the left friction wedge core and right friction wedge core each have a pair of lugs extending from the spring set surface defining face, and wherein the left half center core rests upon the left friction wedge core lugs, and the right half center core rests upon the right friction wedge core lugs.
 10. The coring arrangement of claim 1 wherein the left top half end core and right top half end core each have pair of core prints extending from their top wall defining face into the mold.
 11. The coring arrangement of claim 1 wherein the left bottom half end core and right bottom half end core each have an upper surface, and the left top half end core and right top half end core each have a bottom surface, and the left bottom half end core and right bottom half end core each have a plurality of lugs extending from their upper surface into corresponding openings in the left top half end core and right top half end core bottom surfaces.
 12. The coring arrangement of claim 11 wherein each of the plurality of lugs has a top face, and the corresponding openings in the left top half end core and right top half end core bottom surfaces have upper faces, and the top faces of the plurality of lugs are spaced from the upper faces of the left top half end core and right top half end core openings.
 13. The coring arrangement of claim 1 wherein the left bottom half end core and right bottom half end core each have a shelf, and wherein the left half center core and right half center core each have a weight bearing surface, the left bottom half end core shelf resting upon the left half center core weight bearing surface, and the right bottom half end core shelf resting upon the right half center core weight bearing surface.
 14. The coring arrangement of claim 1 wherein the left half center core and right half center core each have a pair of core prints extending from their bottom wall defining face into the mold.
 15. The coring arrangement of claim 1 wherein the bolster has a center bowl, the center bowl including ledges, the bolster also having a left brake beam opening left of the central transverse plane in each of the opposing side walls, and a left side window in each of the opposing side walls left of the central transverse plane, and wherein the left half center core defines the left brake beam openings and left side windows.
 16. The coring arrangement of claim 15 wherein the bolster has a main pattern parting line, and a left brake beam core print protruding from each of the left half center core side wall defining faces to form the left brake beam openings, the left brake beam core prints extending between the left brake beam openings and the main pattern parting line.
 17. The coring arrangement of claim 16 wherein each left brake beam core print protrudes into the mold and forms a portion of one center bowl ledge.
 18. The coring arrangement of claim 17 wherein each of the bolster opposing side walls has a top and a bottom and a width, and the width of the bolster side wall at the bottom of each side wall is equal to or less than the width of the bolster side wall at any point between the bottom and the top of the side wall.
 19. The coring arrangement of claim 1 wherein the bolster has a center bowl, the center bowl including ledges, the bolster also having a right brake beam opening right of the central transverse plane in each of the opposing side walls, and a right side window in each of the opposing side walls right of the central transverse plane, and wherein the right half center core defines the right brake beam openings and right side windows.
 20. The coring arrangement of claim 19 wherein the bolster has a main pattern parting line, and a right brake beam core print protruding from each of the right half center core side wall defining faces to form the right brake beam openings, the right brake beam core prints extending between the right brake beam openings and the main pattern parting line.
 21. The coring arrangement of claim 20 wherein each right brake beam core print protrudes into the mold and forms a portion of one center bowl ledge.
 22. The coring arrangement of claim 21 wherein each of the bolster opposing side walls has a top and a bottom and a width, the width of the bolster side wall at the bottom of each side wall is equal to or less than the width of the bolster side wall at any point between the bottom and top of the side wall.
 23. The coring arrangement of claim 15 wherein the bolster has a main parting line, and a left side window core print protrudes from each of the left half center core side wall defining faces to form the left side windows, the left side window core prints extending between the left side windows and the main pattern parting line.
 24. The coring arrangement of claim 23 wherein each of the bolster opposing side walls has a top and a bottom and a width, the width of the bolster side wall at the bottom of each side wall is equal to or less than the width of the bolster side wall at any point between the bottom and top of the side wall.
 25. The coring arrangement of claim 15 wherein the bolster has a main parting line, and a right side window core print protrudes from each of the right half center core side wall defining faces to form the right side windows, the right side window core prints extending between the right side windows and the main pattern parting line.
 26. The coring arrangement of claim 25 wherein each of the bolster opposing side walls has a top and a bottom and a width, the width of the bolster side wall at the bottom of each side wall is equal to or less than the width of the bolster side wall at any point between the bottom and top of the side wall.
 27. A coring arrangement for casting a railcar bolster, the coring arrangement located in a mold, the bolster having hollow sections and a left end and right end, the bolster also having a top wall, a bottom wall, and a pair of opposing side walls connecting the top wall and bottom wall, the bolster further having a central transverse plane, a pair of left friction shoe pockets, and a pair of right friction shoe pockets, the pair of left friction shoe pockets and pair of right friction shoe pockets each having inner and outer walls, the coring arrangement comprising: a left half center core having faces defining an internal surface of each of the bolster top wall, bottom wall, and opposing side walls from the bolster central transverse plane to a point between the pair of left friction shoe pocket inner and outer walls; a right half center core having faces defining an internal surface of each of the bolster top wall, bottom wall, and opposing side walls from the bolster central transverse plane to a point between the pair of right friction shoe pocket inner and outer walls; a left top half end core having faces defining an internal surface of the bolster top wall, and an internal surface of each opposing side wall from a point between the left friction shoe pocket inner and outer walls to the left end of the bolster; a left bottom half end core having faces defining an internal surface of the bolster bottom wall, and an internal surface of each opposing side wall from a point between the left friction shoe pocket inner and outer walls to the left end of the bolster; a right top half end core having faces defining an internal surface of the bolster top wall, and an internal surface of each opposing side wall from a point between the right friction shoe pocket inner and outer walls to the right end of the bolster; and a right bottom end core having faces defining an internal surface of the bolster bottom wall, and an internal surface of each opposing side wall from a point between the right friction shoe pocket inner and outer walls to the right end of the bolster.
 28. A railcar bolster, the bolster having a central transverse plane and a central longitudinal plane, the bolster comprising: a top wall; a bottom wall; a pair of opposing side walls connecting the top wall and bottom wall; and the bolster bottom wall having at least four bottom wall openings, two bottom wall openings on either side of the bolster central transverse plane and central longitudinal plane.
 29. The railcar bolster of claim 28 wherein each bottom wall opening accommodates a bottom wall opening core print extending through the opening.
 30. A railcar bolster having a left end and a right end, the bolster comprising: a top wall; a bottom wall; a pair of opposing side walls connecting the top wall and bottom wall; a central transverse plane; a pair of left friction shoe pockets; a pair of right friction shoe pockets; the pair of left friction shoe pockets and pair of right friction shoe pockets each having inner walls and outer walls; a pair of left top end openings in the bolster top wall between the bolster left end and the inner walls of the pair of left friction shoe pockets; a pair of right top end openings in the bolster top wall between the bolster right end and the inner walls of the pair of right friction shoe pockets; each top end opening accommodating a top end opening core print extending therethrough.
 31. A railcar bolster having a left end and a right end, the bolster comprising: a top wall; a bottom wall; a pair of opposing side walls connecting the top wall and bottom wall; a central transverse plane; a pair of left friction shoe pockets; a pair of right friction shoe pockets; the pair of left friction shoe pockets and pair of right friction shoe pockets each having inner walls and outer walls; a pair of left bottom end openings in the bolster bottom wall between the outer walls of the pair of left friction shoe pockets and the bolster central transverse plane; a pair of right bottom end openings in the bolster bottom wall between the outer walls of the pair of right friction shoe pockets and the bolster central transverse plane; and each bottom end opening accommodating a bottom end opening core print extending therethrough.
 32. A railcar bolster having a left end and a right end, the bolster comprising: a top wall; a bottom wall; a pair of opposing side walls connecting the top wall and bottom wall; a central transverse plane; a pair of left friction shoe pockets; a pair of right friction shoe pockets; the pair of left friction shoe pockets and pair of right friction shoe pockets each having inner walls and outer walls; the bolster bottom wall having at least four bottom wall openings, two bottom wall openings on either side of the bolster central transverse plane and central longitudinal plane; each bottom wall opening accommodates a bottom wall opening core print extending through the opening; a pair of left top end openings in the bolster top wall between the bolster left end and the inner walls of the pair of left friction shoe pockets; a pair of right top end openings in the bolster top wall between the bolster right end and the inner walls of the pair of right friction shoe pockets; each top end opening accommodating a top end opening core print extending therethrough; a pair of left bottom end openings in the bolster bottom wall between the outer walls of the pair of left friction shoe pockets and the bolster central transverse plane; a pair of right bottom end openings in the bolster bottom wall between the outer walls of the pair of right friction shoe pockets and the bolster central transverse plane; and each bottom end opening accommodating a bottom end opening core print extending therethrough.
 33. A method of casting a railcar bolster comprising the steps of: inserting cores into a mold to define internal surfaces of the bolster, the cores being made in coreboxes, the cores including a left half center core, a right half center core, a left top half end core, a right top half end core, a left bottom half end core, a right bottom half end core, a left friction wedge core, and a right friction wedge core; the left half center core and right half center core being identical; the left top half end core and right top half end core being identical; the left bottom half end core and right bottom half end core being identical; the left friction wedge core and right friction wedge core being identical; and wherein all of the cores are made in two coreboxes.
 34. The method of claim 33 wherein the left half center core and one of the left friction wedge core or right friction wedge cores are made in one corebox.
 35. The method of claim 33 wherein the right half center core and one of the left friction wedge core or right friction wedge cores are made in one corebox.
 36. The method of claim 33 wherein the left top half end core and left bottom half end core are made in one corebox.
 37. The method of claim 33 wherein the right top half end core and right bottom half end core are made in one corebox.
 38. A method of casting a railcar bolster comprising the steps of: inserting cores into a mold to define internal surfaces of the bolster, the cores being made in coreboxes, the cores including a left half center core, a right half center core, a left top half end core, a right top half end core, a left bottom half end core, a right bottom half end core, a pair of left friction shoe pocket cores, and a pair of right friction shoe pocket cores; the left half center core and right half center core being identical; the left top half end core and right top half end core being identical; the left bottom half end core and right bottom half end core being identical; the pair of left friction shoe pocket cores and pair of right friction shoe pocket cores being identical; and wherein all of the cores are made in two coreboxes.
 39. The method of claim 38 wherein the left half center core and one of the pairs of left friction shoe pocket cores or pairs of right friction shoe pocket cores are made in one corebox.
 40. The method of claim 38 wherein the right half center core and one of the pairs of left friction shoe pocket cores or pairs of right friction shoe pocket cores are made in one corebox.
 41. The method of claim 38 wherein the left top half end core and left bottom half end core are made in one corebox.
 42. The method of claim 38 wherein the right top half end core and right bottom half end core are made in one corebox. 